1. Field
Example embodiments relate to a power device and/or a manufacturing method thereof, and for example, to a high electron mobility transistor having reduced threshold voltage variation and/or a method of manufacturing the same.
2. Description of the Related Art
A high electron mobility transistor (HEMT) may include compound semiconductors having different polarizabilities. A 2-dimensional electron gas (2DEG) may be formed in a channel layer and used as a carrier. When a HEMT includes a thick AlGaN barrier layer, the concentration of 2DEG in a channel layer may increase so that a current during turn-on, that is, an ON current, may increase. Yet, when the thickness of the AlGaN barrier layer is thick, a degree of an energy band of the AlGaN barrier layer being raised by a depletion layer formed between a gate and the AlGaN barrier layer is small. Thus, the 2DEG may not be completely removed from the channel layer under the gate so that an operation of an enhanced mode (E-mode) of the HEMT may be difficult.
Some HEMTs include a recess in the AlGaN barrier layer under the gate. However, the thickness of the AlGaN barrier layer remaining under the recess may vary in an etch process to form the recess. Accordingly, the thickness of the AlGaN barrier layer remaining under the recess may be different for each HEMT. Accordingly, a threshold voltage Vth for turn-on may vary for each HEMT.